Out of the 6 people I would consider "regular" guys I ride with... 3 of us ride fixed... so it's not completely unwelcome
I wouldn't bat an eye at riding fixed on the MS... I mean, yeah, there's 13,000 riders.... that means the road is probably packed for 4 feet in front of me and 40 feet behind me... I don't see how that is any different than the start or rest stops at any other ride of 100+ riders.

Now the hills... that's a different story... but that's why god invented flip-flop hubs (and I addressed that in my first post in this thread... which was MANY fixed miles ago )